Javascript / JQuery条件替换

Question

我在javascript中有一个变量：

var myvar = "0711111111";

我基本上需要做一个条件说：

if (myvar's first character = '0') or (myvar's first character = '+') {

then ... replace the first character with 'somethingelse';

}

Answer 1

var myvar = "0711111111";

if (myvar.charAt(0) == '0' || myvar.charAt(0) == '+') {
   // Replace the char in pos 0 with desired char (now using '=')
   myvar = myvar.replace(myvar.charAt(0), '=')  

}

---

Output: "=711111111"

Answer 2

var myvar = "0711111111";

if(myvar[0] == "0" || myvar[0] == "+"){

    myvar = myvar.substring(1);

}

或使用charAt()

  if(myvar.charAt(0) == "0" || myvar.charAt(0) == "+"){

        myvar = myvar.substring(1);

    }

或使用substring()

 if(myvar.substring(0,1) == "0" || myvar.substring(0,1) == "+"){

            myvar = myvar.substring(1);

   }

Fiddle

Answer 3

var myvar = "0711111111";

if(myvar[0] == "0" || myvar[0] == "+"){

    myvar[0] = "$"; // U can replace

}

Answer 4

将myvar[0]的第一个字符与其他两个字符进行比较

var firstchar = myvar[0]; //or myvar.charAt(0) for ie7 and older support

if ( firstchar === '0' || firstchar === '+' ) {
    // do stuff
    myvar = myvar.replace( firstchar, 'X' ); // where X is the new character
}

Answer 5

请试试这个！

var myvar =     "0711111111" , repWithChar  =   "x";
var firstChar   =   myvar.charAt(0);
if ((firstChar === "0") || (firstChar === "+")) {
  console.log( myvar.replace(myvar.charAt(0), repWithChar) );
}

输出：x711111111